A mysterious Stonehenge bluestone slide

I have been sent some photos relating to British geological sites by a gentleman who recently acquired them.  He wants to remain anonymous, but is happy for the images to be reproduced here.  They seem to have been made by a professional slide maker called AT Davies, but it is a mystery whether he is the same "Davies" who seems to have worked with Teall and Cunnington around 1870 - 1890 in the collecting and examination of igneous fragments from Stonehenge.

The thin section reproduced here, labelled as a diabase from Stonehenge, is at two different magnifications and seen through crossed polars.  It is probably not an "official" slide" in that it has no Geological Survey or Natural History Museum number.

In their paper about HH Thomas in 2018, Richard Bevins and Rob Ixer say as follows:

"In looking at these collections of specimens in more detail, we can see that Thomas examined almost entirely (if not exclusively) debris material from Stonehenge. The Cunnington samples were clearly all debris material. The survey daybook records E1987– 99 as being specimens collected and presented to the Museum of Practical Geology, Jermyn Street, by W. Cunnington, FGS, and adjacent entries suggest that they were donated in 1893 (falling between the entries for 20 March and 5 June 1893). This appears to be a subset of Cunnington’s samples, a more complete set of which were examined and described by Maskelyne (1878), Cunnington (1884) and Teall (1894), and which Harrison et al. (1979) recorded as being collected from excavations at Stonehenge between 1876 and 1881. Curiously, Thomas records some of the Cunnington samples (specifically E1994 and E1993; his pl. XXII, fig. 3 and pl. XXIII, fig. 3, respectively) as being fragments collected by W. Gowland. This is clearly in error, as is his reference to an axiolitic-type rhyolite as being sample E1977 (1923: 251), the latter being a Geological Survey sample collected from the Isle of Man. We think that this should read E1993. Gowland excavated at Stonehenge in 1901, and debris material from Gowland’s excavations was acquired by the Natural History Museum in 1914 (sample numbers BM1914.1–1914.37), so it is probable that Thomas also had access to this as well. Interestingly, however, Thomas makes no reference to these samples."

Maybe it is a different Davies, since the owner of the slide says that AT Davies became a fellow of the RMS in 1916 -- so that would date the slide to that date at the earliest.  But it is possible that this slide will have been seen by HH Thomas while he was working on his Stonehenge bluestones paper which was published in 1923.

Alfred Thomas Davies lived from 1850 to 1934.  The slide is labelled "diabase", and I assume it is unspotted dolerite with an ophitic texture -- but I stand to be corrected.  (When I studied optical mineralogy I hated it with a passion, and absorbed virtually no information!  Ixer and Bevins would be appalled at my lack of judgment....!!)  But that was a very long time ago.

Here is a picture of the little cabinet of slides -- the labelling is somewhat erratic, but there is some interesting material in there!